As Life & Style revealed earlier this week, Kate Middleton is four months pregnant with baby No. 3 — and she couldn't be more excited to expand her and hubby Prince William's royal brood!

“They want their kids to be very close to each other in age so they can grow up as a close-knit family," an insider reveals, which is similar to how William, 34, and his brother Prince Harry, 31, were raised.

The couple, who are already parents to George, 2, and Charlotte, 14 months, “hopes the brothers and sisters can all help each other out as they become full-time working members of the royal family," the insider adds.

"It is very important to William and Kate that, when George becomes king someday, he has the support of his siblings. They don’t want him to be isolated.”

We can't wait to see more of Kate's chic maternity style in the lead-up to her Christmas due date!

For more info on the royal pregnancy, pick up the latest issue of Life & Style, on newsstands now!